The Ministry of Economic Development's Energy Data File June 2008 showed that total petroleum production in 2007 was 88 petajoules, of which 66PJ was produced by Pohokura and Tui.

The publication said 2007's rapid increase in oil production had reversed the declining trend seen in domestic production since 1997.

Furthermore, 2007 was the first year since 1982 that the offshore Taranaki Maui gas-condensate field had not been the top producing field, with both Pohokura and Tui producing more than Maui.

Maui was dominant in 2006, accounting for about 58% of all liquids production, but its share plummeted to only 14% last year when Tui came on stream, accounting for 45% of total production.

Pohokura, which had first gas to shore in August 2006, accounted for 14% of liquids production that year, climbing to 31% in 2007.

Total liquids production was up from 6.66 million barrels in 2006 to 14.87MMbbl last year.

New Zealand's average liquids production - from 17 onshore and offshore Taranaki fields - during 2007 exceeded 40,750 barrels per day, with Tui contributing for only five months. So far this year Tui production alone has been averaging more than 42,000bpd.

The publication said production from Pohokura was about 8200bpd of condensate and 130 million cubic feet per day of gas last year.

But that level of overall production is set to rise markedly when the offshore Maari oil field comes onstream later this year and even further when the Kupe gas-condensate field starts production from mid-2009.

Anticipated production from Maari will initially reach about 35,000bpd of crude, and production from Kupe will initially reach about 4650bpd of condensate and 55MMcf/d of gas.

New Zealand's self-sufficiency in oil - domestic oil production divided by total domestic consumption (including refinery and industry own uses) - peaked in 1997 at 55%, decreased to just 14% in 2006, but jumped last year to 32%.

The report added the medium-term outlook for oil and condensate production is the best it has been since oil production began from the Maui B lobe in the early 1990s.

Total remaining 2P (proved and probable) oil reserves, from producing and non-producing fields, increased from 97.1MMbbl in 2006 to 148.3MMbbl as at last January.

Tui accounted for about 35MMbbl of this increase. More recently operator Australian Worldwide Exploration upgraded Tui's total reserves to 50.1MMbbl.

Remaining liquids reserves at Pohokura increased by 30% to 55.9MMbbl (based on new total reserves estimate of 61.6MMbbl), while reserves at Maui rose 9% to 24.1MMbbl.

Total gas production increased from about 164PJ in 2006 to just over 180PJ in 2007.

Total remaining 2P gas reserves increased 10% to 2.03 trillion cubic feet, driven by a 16% gain at Pohokura to 907.8 billion cubic feet (total original reserves were about 979.8Bcf).

There was also a 13% improvement in remaining Maui gas reserves (to 439Bcf), while smaller gains at Todd Energy's Mangahewa field and other onshore Taranaki fields also contributed.

Wellington-based energy analyst John Kidd told PetroleumNews.net that it was interesting that coal seam methane was mentioned and included in the reserves for the first time.

The MED mentions only one CSM development, Brisbane's Chartwell Energy and Macdonald Investments' PMP 50100 joint venture - NZ's first CSM mining licence - near the West Coast town of Greymouth, with indicative P50 gas reserves for the field of about 171.3Bcf.

Other CSM players include Solid Energy and Denver-based Resource Development Technology, L&M Coal Seam Gas Company, and listed L&M Petroleum - each of which believes CSM reserves of up to 300Bcf lie within their respective permits in Waikato, Otago and Southland.

The MED said exploration and development activity remained high by New Zealand standards in 2007 - 42 wells were drilled, a large increase over the 30 wells drilled in 2006.

The 42 wells were drilled in a number of geological Basins - onshore and offshore Taranaki, onshore East Coast, West Coast and Western Southland. Of these, 26 were exploration wells and 16 were appraisal or development wells. Seventeen offshore wells were drilled, an increase of 10 offshore wells over 2006.

Kidd said the overall result from the Energy Data File was good.

"It is encouraging that additions to the reserve base continue to strongly outpace consumption," he told PNN.